Postnet Edenvale overcharges

I visited Postnet Edenvale on 03 January 2023 to send my British passport renewal documents to the UK. I was charged R650 for DHL courier. A friend went to Postnet Meadowdale last week for the same thing, and was charged R585. I returned to Edenvale branch to ask about the discrepancy, and Dean assured me that each branch was allowed to charge what they liked! I phoned Postnet Edenglen today and was told the charge is R585 and it is regulated through all branches. I have registered my complaint about Postnet Edenvale with the Postnet Head Office.